1. Field of the Invention
The present invention relates to a method of bonding an IC unit having a plurality of IC devices to connection terminals formed on a substrate.
2. Description of the Related Art
A conventional bonding structure, which has an IC (Integrated Circuit) unit formed by TAB (Tape Automated Bonding) method and a LCD (Liquid Crystal Display), is known. The IC unit includes an IC device and a plurality of lead terminals. The LCD, for use in an apparatus such as a television or a large screen, includes electrodes terminals.
Quite a few display driver chips need to be used in a LCD for a television or a large screen. But, each of IC units used to connect a display driver chip to the LCD, contains only one IC device (display driver chip) mounted on a carrier tape. In other words, in this conventional structure, the number of IC units corresponds to that of IC devices to be connected to the LCD. Thus, a number of IC units must be bonded for connecting electrode terminals of the LCD and a printed circuit board, aligning each of lead terminals of the IC unit with a corresponding electrode terminal of the LCD.
In addition, corresponding lead terminals of the display driver chips (IC devices) connected to the LCD must be connected with each other. In this case, since a wiring pattern of mutual connection crosses other lead terminals, patterning of the mutual connection wiring pattern is complicated. Therefore, in a conventional structure, the mutual connection wiring pattern is formed on the printed circuit board.
In the above method of bonding a single IC device (display driver chip) to finger leads of a single film of a carrier tape, however, positioning to the printed circuit board must be performed for each IC unit. Therefore, a connection operation cannot be performed efficiently, and the yield is low due to a positioning or connection failure at a connection portion. In addition, a complicated wiring pattern for an image processing circuit, a control circuit, a memory circuit and the like must be formed on the printed circuit board. Therefore, if the mutual connection pattern of lead terminals of the display driver chips is formed on the wiring substrate (printed circuit board), very complicated wiring patterning must be performed on the substrate as a whole. As a result, the wiring substrate is enlarged in size, and the manufacturing yield is degraded.